Newborn screening for biochemical genetic disorders stands ready to expand coverage to an increasing number of disorders with the application of tandem mass spectrometry. Currently, only a few states have authorized such screening while most others await information on its public health implications. The primary objective of this study, first begun in 1999, is to compare newborn identification by expanded screening to clinical identification in children with biochemical genetic disorders in terms of the health and development of affected children and psychosocial consequences for families. The study also assesses the impact of a false positive screen compared to a normal screen in terms of parental response and interactions with the healthcare system. [unreadable] [unreadable] Continuation of this study increases the sample size of children with similar disorders and permits comparisons of children at similar ages, since clinically diagnosed children generally come to attention later than newborn-screened children. The longer-term implications for families can also be assessed. As a supplement to the earlier study, cost effectiveness analyses will be incorporated to quantify the projected health benefits, health risks and costs of expanded newborn screening, including quality of life measures (utilities) associated with false positive test results. [unreadable] [unreadable] Mothers and fathers of infants diagnosed with metabolic disorders through expanded newborn screening in Massachusetts, Maine and Pennsylvania and parents of children diagnosed with the same set of metabolic disorders in New England States, where expanded newborn screening has not been authorized, will participate in the study. Six months after the diagnosis is confirmed, parents are interviewed and children are administered a medical and neurodevelopmental evaluation. Follow-up interviews and child assessments are administered annually. Mothers and fathers of infants screened false positive (due to an initial specimen in which an abnormality is found but which does not ultimately indicate a disorder) and a control group (parents randomly selected form the public birth registry) are interviewed over the phone when their infants are 6 months old. Primary data from parent interviews and the New England Newborn Screening Program, as well as secondary data from published reports and a panel of experts will be used as inputs to the cost-effectiveness model. [unreadable] [unreadable]